<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .banner{
            width: 300px;
            height: 400px;
            background-color: red;
        }
        .son{
            position: absolute;
            left: 12px;
            width: 40px;
            height: 50px;
            background-color: plum;
        }
    </style>
</head>
<body>

<div class="banner">
    <div class="son">

    </div>
</div>
</body>
</html>